English: British officers with a captured German anti-tank gun in Bapaume, France, during World War I. This photograph of British officers with a German anti-tank gun is evidence of how quickly military technology had to evolve during World War I. The first tanks were introduced by Britain at the Somme in September 1916 and shortly thereafter Germany began developing anti-tank weaponry. One of the most celebrated examples was the 13mm Mauser Tank-Gewehr M1918 anti-tank rifle.

The British advance on Bapaume, a highly successful offensive, provided official war photographers like Tom Aitken with opportunities to take photographs that would raise morale amongst the British public. This is one such opportunity.
[Original reads: 'OFFICIAL PHOTOGRAPH TAKEN ON THE BRITISH WESTERN FRONT IN FRANCE. Our advance on BAPAUME. In a German trench. Two of our officers with a German anti-tank gun.']

http://digital.nls.uk/74549176